1. Field of the Invention
This invention relates to compositions comprising an electrically conductive polymer.
2. Introduction to the Invention
Known electrically conductive polymers include polysulphur nitrides, aniline polymers (i.e. polymers of aniline and/or a substituted aniline), pyrrole polymers (i.e. polymers of pyrroles and/or substituted pyrroles) and polyacetylenes. Although some polymers, e.g. (SN).sub.x, are intrinsically conductive, many polymers require oxidation (or reduction) to render them significantly electrically conductive, or can have their conductivity substantially enhanced by oxidation or reduction. For example, polyacetylenes require oxidation or reduction, and polypyrroles require oxidation. The process of oxidation (or reduction) is referred to herein as "doping". A counter-ion is required to associate itself with the oxidised (or reduced) polymer to balance the ionic charges therein, and such counter-ions and the materials used to provide them are referred to herein as "dopants". Examples of dopants include BF.sub.4.sup.-, p-toluene sulphonate and Br.sup.-.
The term "electrically conductive polymer" is used herein to mean any polymer (including oligomer) which is inherently or intrinsically capable of electrical conductivity, regardless of whether or not it has been rendered electrically conductive by doping or is capable of being rendered electrically conductive by doping. The term "electrically conductive" is used to include materials which are semi-conductive as well as those which are conductive. Examples of electrically conductive polymers include inorganic polymers such as the polysulphur nitrides, and organic polymers such as the polypyrroles, and particularly includes the organic polymers whether in the "doped" electrically more conductive state, or in the "undoped" or "de-doped" electrically less conductive state.